1. Field of the Invention
The present invention related to a molding tool for sealant and a sealing method using the molding tool, whereby an outer surface of the sealant after sealing a jointed part of two members, for instance, a jointed part of exterior panels such as roof panels or the like of an automobile, especially, a jointed part at the bottom of a groove defined when the roof panels are jointed is refined in good shape.
2. Conventional Art
Generally, exterior panels, e.g., roof panels of an automobile or the like are jointed by riveting or spot welding or the like manner. The exterior panels are usually jointed before an undercoating thereof, and after undercoating, the jointed part is sealed by a sealant for the purpose of prevention of water leakage. Thereafter, the whole of the exterior panel including the jointed part is processed through face coating. More specifically, in jointing roof panels of an automobile, a jointed part 107 is located at a bottom 106 of a roof groove 105 as indicated in FIGS. 11 and 12. The rain or the like is apt to gather in this roof groove 105, and therefore it is required to surely seal the jointed part 107. It is to be noted here that the roof groove 105 referred to above is a groove defined when a stepped part 102 at each side edge of a main roof panel 101 is overlaid and jointed to a stepped part 104 at a side edge of a sub roof panel 103 which is to be jointed to the main roof panel although only one roof groove 105 among the grooves formed at both edges of the main roof panel 101 is represented in FIGS. 12 and the other drawings.
In order to securely seal the jointed part 107, conventionally, a sealant has been provided at the surface of the jointed part 107 to enhance the sealing properties at the jointed part 107. For the sealant, such type of a sealant is used that is set with heat from the paste-like state, or melted or softened and thereafter hardened or solidified when receiving heat from the state of a solid rod or tape at normal temperatures. The sealant is formed of a thermoplastic or thermosetting composition including an epoxy resin, a urethane resin, an olefin resin, a vinyl chloride resin, an acrylic resin, an ethylene-vinyl acetate copolymer, etc. Japanese Patent Laid-Open Publication Nos. 54-106548 (106548/1979), 3-273975 (273975/1991), etc. relate to the above kind of sealant and a sealing method using the sealant.
In general, both the aforementioned paste-like sealant before solidified or hardened and the melted or softened sealant are considerably viscous liquid, and an outer surface 108 of the sealant is easy to finish rough as shown in FIG. 13, thus deteriorating the appearance of the sealant after sealing the jointed part 107. Moreover, even in the case where the viscosity of the sealant is relatively low to allow a projection/recess of the outer surface 108 to be coated smooth and flat, the outer surface 108 is prone to generate a projection/recess 110 corresponding to a recessed part 109 of the spot-welded part which is the jointed part 107, as in FIG. 14.
Further, as shown in FIG. 15, the main roof panel 101 is jointed to the sub roof panel 103 with a gap 112 formed between an edge 111 of the stepped part 102 of the main roof panel 101 and the stepped part 104 of the sub roof panel 103. The gap 112 is turned to a recessed part, corresponding to which the outer surface 108 of the sealant is made rough. Besides, the main roof panel 101 jointed to the sub roof panel 103 by a jointing means, for example, spot welding or the like is often corrugated in the longitudinal direction thereof, consequently degrading the appearance of the sealant at the roof groove 105 not a little.
For preventing the inferior or defective appearance of the sealant from being noticed from outside, by way of example, a decorative member 113 called as a roof molding has been sometimes attached to the roof groove 105 to cover the sealant as indicated in FIG. 16. This method is disadvantageous, though, in that the number of parts and working processes is increased. Since the roof molding is a separate part from the roof panel, the roof molding should be painted with the same color beforehand as that of the roof panel or the total of the roof panel should be painted again after the roof molding is installed so as to keep the roof in the same color. The number of working steps is undesirably increased.
An object of the present invention is to provide a molding tool for sealant and a sealing method using the molding tool whereby the outer surface of the sealant is refined in good shape without increasing the number of parts and working steps.